U.S. patent number 7,225,035 [Application Number 10/876,003] was granted by the patent office on 2007-05-29 for multipolar medical electrical lead.
This patent grant is currently assigned to Medtronic, Inc.. Invention is credited to Scott J. Brabec, Douglas S. Hine.
United States Patent |
7,225,035 |
Brabec , et al. |
May 29, 2007 |
Multipolar medical electrical lead
Abstract
A pacing lead includes a first pacing cathode coupled to a first
conductor, a second pacing cathode coupled to a second conductor,
and a flexible anode coupled to a third conductor. The flexible
anode has a length less than approximately 10 millimeters and is
spaced apart from and proximal to the first pacing cathode and
spaced apart from and distal to the second pacing cathode. The
spacing between the anode and the first pacing cathode is
approximately equal to the spacing between the anode and the second
pacing cathode.
Inventors: |
Brabec; Scott J. (Elk River,
MN), Hine; Douglas S. (Forest Lake, MN) |
Assignee: |
Medtronic, Inc. (Minneapolis,
MN)
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Family
ID: |
35134162 |
Appl.
No.: |
10/876,003 |
Filed: |
June 24, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050288761 A1 |
Dec 29, 2005 |
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Current U.S.
Class: |
607/122; 607/116;
607/119 |
Current CPC
Class: |
A61N
1/056 (20130101); A61N 2001/0585 (20130101) |
Current International
Class: |
A61N
1/05 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 571 797 |
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Sep 1998 |
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EP |
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WO 02/053225 |
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Jul 2002 |
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WO |
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WO 057311 |
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Jul 2003 |
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WO |
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Primary Examiner: Layno; Carl
Attorney, Agent or Firm: Soldner; Michael C. Barry; Carol F.
Wolde-Michael; Girma
Claims
What is claimed is:
1. A medical electrical lead, comprising: an elongate lead body
including a first conductor, a second conductor and a third
conductor extending therein and electrically isolated from one
another; a first cathode electrode coupled to the first conductor;
a second cathode electrode coupled to the second conductor; and a
flexible anode electrode having a length less than approximately 10
millimeters and a surface area greater than a surface area of each
of the first cathode electrode and the second cathode electrode,
being coupled to the third conductor, spaced apart from and
proximal to the first cathode electrode and spaced apart from and
distal to the second cathode electrode, the spacing between the
anode electrode and the first cathode electrode being approximately
equal to the spacing between the anode electrode and the second
cathode electrode.
2. The lead of claim 1, wherein a length of the flexible anode
electrode is between approximately 3 millimeters and approximately
10 millimeters.
3. The lead of claim 2, wherein the length is approximately 8
millimeters.
4. The lead of claim 1, wherein an outer diameter of the flexible
anode electrode is between approximately 0.75 millimeters and
approximately 2 millimeters.
5. The lead of claim 4, wherein the outer diameter is approximately
1.3 millimeters.
6. The lead of claim 1, wherein a length of the flexible anode
electrode is between approximately 3 millimeters and approximately
10 millimeters and an outer diameter of the flexible anode
electrode is between approximately 0.75 millimeters and
approximately 2 millimeters.
7. The lead of claim 1, wherein the first cathode electrode is
positioned proximal to a distal end of the lead body.
8. The lead of claim 1, wherein the first cathode electrode
terminates a distal end of the lead body.
9. The lead of claim 1, wherein the flexible anode electrode
comprises a conductive polymer.
10. The lead of claim 1, wherein the flexible anode electrode
comprises a coiled conductive wire.
11. The lead of claim 1, wherein the flexible anode electrode
includes a coating to reduce post-pace polarization.
12. The lead of claim 1, wherein a ratio of a surface area of the
flexible anode electrode to a surface area of each of the first
cathode electrode and the second cathode electrode is greater than
approximately 3:1.
13. The lead of claim 12, wherein the ratio is greater than or
equal to approximately 6:1.
14. The lead of claim 1, wherein the spacing between the flexible
anode electrode and the first cathode electrode is between
approximately 5 millimeters and approximately 15 millimeters.
15. The lead of claim 1, wherein the spacing between the flexible
anode electrode and the first cathode electrode is between
approximately 9 millimeters and approximately 15 millimeters.
16. The lead of claim 1, further comprising an in-line connector
terminating a proximal end of the lead body; the in-line connector
comprising a first contact coupled to the first conductor, a second
contact coupled to the second conductor and a third contact coupled
to the a third conductor; wherein the third contact is positioned
distal to the first contact and the second contact.
17. The lead of claim 1, further comprising a bifurcated connector
terminating a proximal end of the lead body; the bifurcated
connector including a first contact coupled to the first conductor
and a second contact coupled to the third conductor, the first
contact and the second contact positioned on a first leg, and a
third contact coupled to the second conductor and a fourth contact
coupled to the third conductor, the third contact and the fourth
contact positioned on a second leg.
18. The pacing lead of claim 17, wherein the first contact
terminates a proximal end of the first leg and the third contact
terminates a proximal end of the second leg.
19. The pacing lead of claim 17, wherein each leg of the bifurcated
connector conforms to an industry standard.
20. A method for delivering a pacing pulse to a heart, the method
comprising the steps of: positioning a distal portion of a pacing
lead within a coronary vein, the distal portion including a first
pacing cathode, a second pacing cathode and a flexible anode having
a length less than approximately 10 millimeters and a surface area
greater than a surface area of each of the first pacing cathode and
the second pacing cathode, the flexible anode spaced apart from and
proximal to the first pacing cathode and spaced apart from and
distal to the second pacing cathode, the spacing between the anode
and the first pacing cathode being approximately equal to the
spacing between the anode and the second pacing cathode; selecting
a one of the first pacing cathode and the second pacing cathode to
form a bipolar pair with the flexible anode; delivering a pacing
pulse to the heart via the bipolar pair.
21. The method of claim 20, further comprising the steps of:
applying a test pacing pulse to each of the first pacing cathode
and the second pacing cathode; and measuring pacing thresholds of
the first pacing cathode and the second pacing cathode; and wherein
the step of selecting the one from the first pacing cathode and the
second pacing cathode is based upon the pacing thresholds.
22. The method of claim 20, further comprising the steps of:
applying test pacing pulses to each of the first pacing cathode and
the second pacing cathode; and observing for phrenic nerve
stimulation resulting from the pacing pulses; and wherein the step
of selecting the one from the first pacing cathode and the second
pacing cathode is based upon an absence of phrenic nerve
stimulation.
23. The method of claim 20, further comprising the steps of:
applying test pacing pulses to each of the first pacing cathode and
the second pacing cathode; and observing a hemodynamic response of
the heart resulting from the pacing pulses; and wherein the step of
selecting the one from the first pacing cathode and the second
pacing cathode is based upon the hemodynamic response.
24. The method of claim 20, further comprising the step of sensing
an evoked response of the pacing pulse from the bipolar pair by
means of another of the first pacing cathode and the second pacing
cathode that is not selected.
25. The method of claim 20, wherein: the step of selecting the one
from the first pacing cathode and the second pacing cathode
comprises selecting a connector leg from a first connector leg and
a second connector leg of a bifurcated connector terminating a
proximal end of the lead; wherein the first connector leg includes
a first contact coupled to the first conductor and a second contact
coupled to the third conductor and the second connector leg
includes a third contact coupled to the second conductor and a
fourth contact coupled to the third conductor.
Description
TECHNICAL FIELD
The present invention is directed to implantable medical devices
and more particularly to medical electrical leads including a
plurality of electrodes.
BACKGROUND
Implantable medical electrical stimulation and/or sensing leads are
well known in the field of cardiac stimulation and monitoring, for
example cardiac pacing and/or cardioversion/defibrillation, and in
other fields of electrical stimulation or monitoring, for example
of the central nervous system. In the field of cardiac stimulation
and monitoring, lead electrodes are positioned at an endocardial or
epicardial site and an implantable pulse generator (IPG), pacemaker
or cardioverter/defibrillator, or a monitor is coupled to the heart
through one or more of such endocardial or epicardial leads. Means
for implanting such cardiac leads are known to those skilled in the
art of pacing and defibrillation therapy.
More recently, medical electrical leads have been constructed to
include a plurality of pacing and/or sensing electrodes from which
one or more of the electrodes may be selected in order to optimize
electrical stimulation therapy and/or monitoring. Additionally
leads adapted for deep brain stimulation, and other leads adapted
to stimulate other muscles of the body may include a plurality of
electrodes from which one or more electrodes may be selected to
optimize therapy.
BRIEF DESCRIPTION OF THE DRAWINGS
The following drawings are illustrative of particular embodiments
of the invention and therefore do not limit its scope, but are
presented to assist in providing a proper understanding of the
invention. The drawings are not to scale (unless so stated) and are
intended for use in conjunction with the explanations in the
following detailed description. The present invention will
hereinafter be described in conjunction with the appended drawings,
wherein like numerals denote like elements, and:
FIG. 1 is a plan view of a medical electrical lead according to one
embodiment of the present invention;
FIG. 2 is a schematic showing the lead of FIG. 1 implanted within a
coronary vasculature;
FIG. 3 is a plan view of a lead connector according to another
embodiment of the present invention; and
FIG. 4 is a plan view of a distal portion of a medical electrical
lead according to another embodiment of the present invention.
DETAILED DESCRIPTION
The following detailed description is exemplary in nature and is
not intended to limit the scope, applicability, or configuration of
the invention in any way. Rather, the following description
provides a practical illustration for implementing exemplary
embodiments of the invention.
FIG. 1 is a plan view of a medical electrical lead 100 according to
one embodiment of the present invention. FIG. 1 illustrates lead
100 including a elongate body 16 carrying a first elongate
conductor 101, a second elongate conductor 102 and a third elongate
conductor 105, each illustrated schematically with dashed lines;
according to one embodiment, lead body 16 is formed of a multilumen
insulative sheath, either silicone or polyurethane, and conductors
101, 102, 105 from cabled bundles of MP35N wires. FIG. 1 further
illustrates lead body 16 terminated at a proximal end by a
connector 17, which includes electrical contacts 120, 110 and 150
coupled to conductors 102, 101 and 105, respectively; lead 100
further includes electrodes 12, 10 and 15 formed about a distal
portion of lead body 16, proximal to a distal end 13 of lead 100,
and coupled to contacts 120, 110 and 150, respectively, via
conductors 102, 101 and 105. Connector 17, an in-line lead
connector, is just one embodiment of many connector types that may
be incorporated; the scope of the present invention includes any
type of lead connector known to those skilled in the art for
coupling a pulse generator device, such as a pacemaker, to a
medical electrical lead.
According to some embodiments of the present invention the distal
portion of lead body 16 is sized to fit within a coronary vein in
order to pace and sense from an epicardial surface of a heart; thus
an outer diameter of electrodes 10, 12 and 15 is less than
approximately 2 mm and according to a particular embodiment a
diameter of flexible electrode 15 is approximately 1.3 mm.
Furthermore, although not shown in FIG. 1, the distal portion of
lead body 16 may include one or more preformed bends to urge
electrodes 10 and 12 into contact with the epicardial surface; an
example of such a lead distal portion is described by Sommer et al.
in U.S. Pat. No. 5,999,858, which is incorporated by reference
herein in its entirety.
An implanted position of lead electrodes is often constrained by
coronary vasculature anatomy, thus embodiments of the present
invention provide at least two options for a pacing electrode
position. FIG. 2 is a schematic showing the lead 100 implanted
within a coronary vasculature. FIG. 2 illustrates electrodes 10, 12
and 15 positioned in a great cardiac vein 28 wherein either a pair
formed by electrode 10 and electrode 15, electrode 10 as cathode
and electrode 15 as anode, or a pair formed by electrode 12 and
electrode 15, electrode 12 as cathode and electrode 15 as anode,
may be selected for stimulation/pacing of a left ventricle 20.
According to some embodiments of the present invention, the
selection is based either upon a pacing/stimulation threshold,
lower being more desirable, or upon an absence of phrenic nerve
stimulation resulting from the pacing from the pair, or upon
hemodynamic response of the heart, for example as observed via
echocardiography, or upon a combination of any of these factors;
selection at time of implant would be determined by delivering test
pulses to each of the pairs and observing the results. According to
another aspect of the present invention, one of electrodes 10 and
12, which is not selected, may be used to sense an evoked response
to pacing/stimulation delivered by the pair including the selected
one of electrodes 10 and 12; the sensing may be bipolar, for
example the unselected electrode in conjunction with electrode 15
or another electrode included on another implanted lead, or
unipolar.
According to common knowledge of those skilled in the art, a
bipolar pacing pair including an anode having a greater geometric
surface area than that of the cathode results in lower pacing
thresholds. According to embodiments of the present inventions a
ratio of a surface area of electrode 15 to a surface area of either
electrode 10 or electrode 12 is greater than approximately 3:1 or
greater than or equal to approximately 6:1. In order to accommodate
an enlarged surface area for electrode 15, embodiments of the
present invention include anode electrode 15 having a flexibility
to navigate within the coronary vasculature; electrode 15 may be
formed by a coiled conductive wire, as illustrated, or by a layer
of a conductive polymer. Examples of suitable wire materials
include, but are not limited to, platinum and tantalum, and
examples of conductive polymers include, but are not limited to
metallic or carbon filled silicone, polyacetylene, polypyrrole and
polyanaline. Embodiments of the present invention may further
include those wherein electrode 15 includes a coating to reduce
post-pace polarization; examples of such coatings include, but are
not limited to, titanium nitride, platinum black and iridium
oxide.
Returning now to FIG. 1, a distance D1 between electrode 10 and
flexible electrode 15 is approximately equal to a distance D2
between electrode 12 and flexible electrode 15 according to
embodiments of the present invention; distances D1 and D2 may be
between approximately 5 mm and approximately 15 mm or between
approximately 9 mm and approximately 15 mm. Furthermore, according
to embodiments of the invention, a length L of electrode 15 is less
than approximately 10 mm, preferably between approximately 3 mm and
approximately 10 mm. According to an exemplary embodiment,
electrode 15 has a length L of approximately 8 mm and a diameter of
approximately 1.3 mm while electrodes 10 and 12 each have a length
of approximately 1 mm and a diameter of approximately 1.6 mm.
FIG. 3 is a plan view of a lead connector 47 according to another
embodiment of the present invention. FIG. 3 illustrates bifurcated
lead connector 47 terminating a proximal end of lead body 16 and
including a first leg 471 and a second leg 472; according to one
embodiment of the present invention first leg 471 and second leg
472 each conform to the IS-1 industry standard. FIG. 3 further
illustrates conductor 101 and a branch 105a of conductor 105
extending into first leg 471 to couple with contact 110 and a
contact 150a, respectively, and conductor 102 and a branch 105b of
conductor 105 extending into second leg 472 to couple with contact
120 and a contact 150b, respectively. According to the illustrated
embodiment, once lead 100 is implanted and one of electrodes 10 and
12 (FIGS. 1 and 2) has been selected as the cathode to function in
conjunction with anode electrode 15, the connector leg
corresponding with the selected cathode, for example leg 471 for
cathode 10 or leg 472 for cathode 12, is connected to a pulse
generator device. The non-selected leg may be capped according to
means known to those skilled in the art.
FIG. 4 is a plan view of a distal portion of a medical electrical
lead 300 according to another embodiment of the present invention.
FIG. 4 illustrates a lead body 316 in the form of an elongate
insulative sheath carrying a multi-filar coiled conductor 313 shown
by dashed lines; coiled conductor 313 includes three sets of filar
pairs 301, 302 and 305 electrically isolated from one another.
According to the illustrated embodiment first filar pair 301 is
coupled to tip electrode 310 at a junction 31, second filar pair
302 is coupled to a proximal electrode 312 at a junction 32, and
third filar pair 305 is coupled to a flexible anode electrode 315
at junction 35. Junctions 31, 32 and 35 may be formed according to
methods known to those skilled in the art, for example by crimps,
stakes or welds. According to an exemplary embodiment of the
present invention, filar pairs 301, 302 and 305 are isolated from
one another by means of a hydrolytically stable polyimide coating
formed about each filar of two or all of the pairs; a similar
multi-filar conductor construction is described in co-pending
patent application U.S. 2003/0216800, which is incorporated by
reference in its entirety herein. According to yet another
embodiment each conductor may be formed as an independent coil
according to a coaxial construction well known to those skilled in
the art. Although not shown, tip electrode 310 may include a
longitudinally extending lumen, in communication with a lumen of
coiled conductor 313, for passage of guidewire therethrough, and a
tip seal; such a configuration is described by Sommer and Hine in
U.S. Pat. No. 6,192,280 which is incorporated by reference herein
in its entirety.
In the foregoing detailed description, the invention has been
described with reference to specific embodiments. However, it may
be appreciated that various modifications and changes can be made
without departing from the scope of the invention as set forth in
the appended claims.
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